Field of the Invention
The present invention relates to a cleaning blade and a cleaning device.
Description of the Related Art
In general, after a toner image formed on the surface (outer peripheral surface) of an electrophotographic photoconductor (hereinafter also simply referred to as a “photoconductor”) is transferred to a transfer material or an intermediate transfer body or also after a toner image is further transferred to a transfer material from an intermediate transfer body, toner is likely to partially remain on the surface of the photoconductor and/or the intermediate transfer body. Therefore, the toner remaining on the surface of the photoconductor or the intermediate transfer body needs to remove. The removal is usually performed by a cleaning blade. As the cleaning blade, a blade like (plate like) one having a thickness (width) of 0.5 mm or more and 3 mm or less and a length in the longitudinal direction of a surface facing a member to be cleaned (a photoconductor, an intermediate transfer body, and the like) longer than the thickness is used, for example.
The cleaning blade is attached to a metal holder and is fixed thereto for use in an electrophotographic apparatus, for example. The cleaning blade is disposed in such a manner that an edge portion (front edge ridgeline portion) of the cleaning blade contacts a member to be cleaned. For the cleaning blade, a cleaning blade formed from urethane rubber is frequently used because the wear resistance, the grade of permanent deformation, and the like are excellent. As toner which has been developed in order to meet a demand for an improvement of image quality in recent years, toner having a small particle diameter and high sphericity (close to a spherical shape) is known. The toner having a small particle diameter and high sphericity has a feature that the transfer efficiency is relatively high and can meet the demand for the improvement of image quality.
However, even when it is attempted to remove the toner having a small particle diameter and high sphericity from the surface of the member to be cleaned using the cleaning blade, the toner having a small particle diameter and high sphericity is difficult to sufficiently remove, so that faulty cleaning occurs in some cases. This is because the toner having a small particle diameter and high sphericity is more likely to pass through a small gap formed between the cleaning blade and the member to be cleaned as compared with toner not having a small particle diameter and high sphericity.
In order to suppress the passing-through of such toner, it is effective to increase the contact pressure between the cleaning blade and the member to be cleaned to reduce the gap.
However, as an increase in the contact pressure between the cleaning blade and the member to be cleaned, there is a tendency for the frictional force between the cleaning blade and the member to be cleaned to be higher.
Then, as an increase in the frictional force between the cleaning blade and the member to be cleaned, the cleaning blade is more likely to be pulled in the moving direction of the surface of the member to be cleaned, so that an edge portion of the cleaning blade is turned up in some cases.
When the cleaning blade resists the turning-up force to return to the original state, an abnormal sound (squeaking) generates in some cases. Particularly in a high temperature and high humidity environment, the adhesion force between the cleaning blade and the member to be cleaned increases to increase the turning-up degree of the edge portion, so that the squeaking is likely to generate.
In order to suppress such squeaking, it is effective to increase the hardness of a cleaning blade contact portion to reduce the frictional force between the cleaning blade and the member to be cleaned to suppress minute vibration.
When the hardness of the surface layer of the cleaning blade is higher, the true contact area with the member to be cleaned surface becomes smaller, so that the frictional force decreases. Japanese patent Laid-Open No. 2010-281974 describes a technique of forming a hard surface layer having a cleaning blade front edge ridgeline portion on one side on the edge face which is a face parallel to the thickness direction of the cleaning blade in such a manner that the layer thickness becomes uneven in the longitudinal direction of the cleaning blade.
Moreover, Japanese Patent Laid-Open No. 2013-190642 describes a technique of providing a cleaning blade having two layers different in 100% modulus, in which a coat layer having a high 100% modulus is provided on an edge portion.
The present invention is directed to providing a cleaning blade in which squeaking does not generate under severe conditions where toner and external additives are hardly supplied and in which surface layer peeling of the cleaning blade and passing-through due to insufficient following properties to unevenness of the surface of a member to be cleaned and foreign substances which may be present on the surface thereof are hard to occur.
Moreover, the present invention is directed to providing a cleaning blade in which vibration of an elastic body portion which is brought into contact with a member to be cleaned is hard to be transmitted to a support member and the contact state to the member to be cleaned of the elastic body portion can be stabilized.
Furthermore, the present invention is directed to providing a cleaning device capable of stably cleaning the surface of a member to be cleaned.